Flexible container for fluids

ABSTRACT

The invention relates to a flexible container for fluids, comprising an inner bag (1) of a thin material and an outer sack (2) of a durable fabric. The outer sack (2) is cylindrical and its mantle surface is provided with channels (4) for receiving support pillars (5) fastened to a wooden pallet (6). At deceleration during the transport of a full container, the upper ends of the forward support pillars exert great spot loads on the outer sack (2). Such loads can be avoided to a great extent if an outer and an inner side wall (8, 9) of the channels (4) are equally broad in the peripheral direction of the outer sack.

The present invention relates to a flexible container for fluids,comprising a liquid-proof inner bag; a substantially cylindrical outersack which surrounds the inner bag and the mantle surface of which isprovided with channels for support pillars, said channels extending inparallel with the central line of the outer sack; and means for fillingand emptying the container.

This type of containers known from the prior art are intended for thetransport and storage of different kinds of fluids, such as liquids,viscous substances, and bulk goods. Such containers are usuallymanufactured in two sizes: five hundred litres and a thousand litres.The containers are disposable and they are transported to the user infolded position. Before filling, support pillars are inserted in thechannels provided in the mantle surface of the outer sack, and thesupport pillars are fastened to a conventional pallet of wood, whichmakes the container easier to displace. The support pillars keep thecontainer in upright position on the pallet.

The support pillars are mounted pivotably to the pallet by means ofparallel metal shafts, which are secured to the pallet and extendthrough the support pillars. This way of mounting is used so as toreduce strains exerted on the support pillars on the pallet.

As mentioned above, the support pillars are positioned in channelsprovided in the mantle surface of the outer sack. The channels areformed by pockets open at the bottom and closed at the top. The pocketsare formed by sewing elongated material strips onto the mantle surfaceof the outer sack, whereby the strips are sufficiently broad for thesupport pillars to be easily inserted into the space between the mantleof the outer sack and the material strip.

During transport, full containers are often exposed to variations in thetransport velocity, whereby retardations in particular may be drastic.At retardation the fluid tends to continue its movement onwards morerapidly than the pallet, wherefore the support pillars swing onwards.The back portion of the sack is thereby lifted upwards along thebackward support pillars, and the upper and lower surface of the sacktakes an inclined position. The outer sack is thereby exposed to highstrains especially at the upper ends of the forward support pillars, butto a certain extent also at the lower ends of the backward supportpillars, which may result in breakage in the outer sack.

The object of the present invention is to provide a container in whichthe above-mentioned strains are considerably reduced as compared withcontainers known from the prior art. The container according to theinvention is characterized in that an outer and an inner side wall ofthe channels have substantially the same dimension in the peripheraldirection of the outer sack.

Channels formed in this way have the advantage that both side walls arestrained when the container is filled, whereby they adhere to thesupport pillar. This results in great friction forces between the sidewalls of the channel and the support pillar so that strains caused byretardation will not focus on the upper end of the forward supportpillars and on the lower end of the backward support pillars. Instead,they are distributed over the whole length of the support pillars. Thedisadvantageous spot load occurring in containers known from the priorart because the container is to some extent movable with respect to thesupport pillars is thereby avoided. As a result of the great frictionforces between the support pillars and the channel wall, the containeraccording to the invention is locked in place with respect to thesupport pillars, which prevents the back portion of the container fromrising up on braking.

The channels according to the invention also have the advantage thatthey do not project from the mantle surface of the outer sack to such anextent as known channels. Therefore the channels are less exposed toshocks as prior channels.

According to a preferred embodiment, both channel walls are integralwith the mantle of the outer sack. When the fabric is formed in this wayknown per se, the two seams in each channel are omitted, which naturallyconsiderably simplifies the manufacture of the container.

A preferred embodiment of the container according to the invention willbe described in more detail in the following with reference to theattached drawing, wherein

FIG. 1 is a perspective view of a container according to the invention;and

FIG. 2 illustrates a detail of the mantle surface of the outer sack in ahorizontal section.

FIG. 1 shows a flexible container comprising a liquid-proof inner bag 1of e.g. a thin polyethylene film; and a cylindrical outer sack 2 whichsurrounds the inner bag and is formed of e.g. a durable polypropylenefabric. The upper end face of the container is provided with a fillingfunnel 3 whereas the lower end face is provided with an emptying valvenot shown.

The mantle surface of the outer sack is provided with four channels 4which are parallel with the central axis of the sack and which areclosed at the top and open at the bottom. A support pillar 5 of e.g.wood is inserted in each channel. Each support pillar is secured to aconventional pallet 6 of wood by means of a metal shaft 7. The shaft isfastened to the pallet and it extends through the support pillar so thatthe pillar is pivotable round the shaft 7 to some extent.

According to the invention the outer side wall 8 of the channels, i.e.,the side wall on the outer side of the support pillar, and the innerside wall 9 on the inside of the support pillar have substantially thesame dimension in the peripheral direction of the outer sack. Thisappears most clearly from FIG. 2. The dimension of the side wall in theperipheral direction of the outer sack refers to the width of the wallbetween lines along which the side walls adjoin to form a single wall.The mantle of the outer sack preferably consists of a fabric which ismanufactured so that the mantle wall and the side walls 8, 9 areintegral with each other.

The container is transported in the position shown in FIG. 1 except thatthe filling funnel 3 is closed. When decelerating a movementperpendicular to the shafts 7, the support pillars 5 are pivoted aroundthe shafts and the container assumes a forwardly inclined position.Thereby the support pillars cause strains on the outer sack especiallyat the upper end of the forward pillars. Due to the high frictionbetween the pillars 5 and the side walls 8, 9 of the channels, the loadis, however, distributed over the whole length of the mantle surface sothat the load is at its maximum at the upper end of the channels and atits minimum at the lower end. This distribution of the forces over alarger area naturally reduces the peak loads.

It is to be understood that in order that the channels would function asdesired the outer side wall 8 must not be broader than the inner sidewall 9. However, the inner side wall may be somewhat broader than theouter one, because the pressure of the fluid in the container pressesthe inner side wall against the support pillar 5.

I claim:
 1. A flexible container for fluids, mounted on a pallet (6) andcomprising a liquid-proof inner bag (1); a substantially cylindricalouter sack (2) which surrounds the inner bag and the mantle surface ofwhich is provided with channels (4) for support pillars (5) pivotablysecured to the pallet (6), said channels extending in parallel with thecentral axis of the outer sack; and means (3) for filling and emptyingthe container, characterized in that an outer and an inner side wall(8,9) of the channels (4) have substantially the same dimension in theperipheral direction of the outer sack (2).
 2. A container according toclaim 1, characterized in that both channel walls (8,9) are integralwith the mantle of the outer sack (2).